The present invention relates to a sheet post-processing apparatus and an image forming apparatus having the same therein, particularly for binding a stack of sheets.
In some prior image forming apparatuses including copiers, printers, facsimile machines and machines combining the same, there is a type such that sheets discharged from an image forming apparatus is piled, and a piled sheet bundle is stapled or stitched together by a sheet post-processing apparatus disposed therein.
Such sheet post-processing apparatuses have a stitching unit having a head unit for driving staples and an anvil unit for receiving and bending the staples driven out of the head unit, thereby stitching the sheet bundle at a plurality of positions thereof.
The prior sheet post-processing apparatus, as disclosed in Japanese Patent Publication (KOKAI) No. 12-84903, has the head unit and the anvil unit of the stitching unit mounted in respective movable holders to relatively move the stitching unit and the sheet bundle. With the head unit and anvil unit mounted in the holders, maintenance for jamming of staple or similar failures can be made easy.
The prior sheet post-processing apparatus needs precise positioning of the head unit and the anvil unit. If the head unit and the anvil unit deviate in position, the staple can not be bent precisely at its tip, resulting in the jamming of the staple.
However, the prior sheet post-processing apparatus has the disadvantage that if the head unit including the driver blade for driving the staple is made detachable, the position of the head unit deviates when the head unit is detached from and attached to the holder for each time maintenance is performed, resulting in irregular stapling.
Also, the prior sheet post-processing apparatus has the disadvantage that if the head unit or the anvil unit is detached from the holder or not positioned precisely in maintenance before saddle stitching, for example, the sheet bundle can not be stapled, or jamming of staple is caused.
In view of the foregoing problem of the prior art, it is an object of the present invention to provide a sheet post-processing apparatus for which maintenance can be easily performed and saddle stitching can be done securely, and an image forming apparatus having the same provided therein.
Further objects and advantages of the invention will be apparent from the following description of the invention.
In order to accomplish the foregoing object, a sheet post-processing apparatus of the invention includes a head portion for driving a staple into a sheet bundle; an anvil portion arranged to face the head portion for receiving and bending the staple driven from the head portion; moving means for relatively moving the head portion, anvil portion and sheet bundle along surfaces of the sheet bundle placed at a stitching position between the head portion and the anvil portion, both surfaces of the sheet bundle opposing the head portion and the anvil portion; a head portion support member for supporting the head portion; and an anvil portion support member for supporting the anvil portion. The head portion comprises a base portion engaging the base portion support member and an attachment portion detachable from the base portion.
In accordance with another aspect of the present invention, a sheet post-processing apparatus includes a head portion for driving a staple into a sheet bundle; an anvil portion arranged to face the head portion for receiving and bending the staple driven from the head portion; moving means for relatively moving the head portion, anvil portion and sheet bundle along surfaces of the sheet bundle placed at a stitching position between the head portion and the anvil portion, both surfaces of the sheet bundle facing the head portion and the anvil portion; a head portion support member for supporting the head portion; and an anvil portion support member for supporting the anvil portion. The anvil portion comprises a base portion engaging the anvil portion support member and an attachment portion detachable from the base portion.
In accordance with a further aspect of the present invention, an image forming apparatus includes an image forming portion; a head portion for driving staples on a sheet bundle delivered in sequence out of the image forming portion and stacked; an anvil portion arranged to face the head portion for receiving and bending the staple driven from the head portion; moving means for relatively moving the head portion, anvil portion and sheet bundle along surfaces of the sheet bundle placed at a stitching position between the head portion and the anvil portion, both surfaces of the sheet bundle opposing the head portion and the anvil portion; a head portion support member for supporting the head portion; and an anvil portion support member for supporting the anvil portion. At least one of the head portion and the anvil portion comprises a base portion engaging the head portion support member or the anvil portion support member, and an attachment portion detachable from the base portion. The apparatus further includes sheet bundle feed means for feeding the sheet bundles stitched by the head portion and the anvil portion; and an accumulating part for accumulating the sheet bundle fed by the sheet bundle feed means.